Potentiometric monitoring of cobalt in beer sample by solid contact ion selective electrode

Abstract

A new solid contact cobalt selective electrode was constructed with 4-tert-butylthiacalix[4] arene as ionophore. The best performance was observed with the membrane having an ionophore/polyvinyl chloride/sodium tetraphenylborate/nitrophenyl octyl ether ratio of 3.5:33:1.5:62 (w/w; mg). The electrode, under steady-state conditions, exhibited a working concentration range of 1 x 10(-1) - 1 x 10(-6) mol/L with a near-Nernstian slope of 25.3 mV/decade and a detection limit of 3.5 x 10(-7) mol/L. The electrode had a very short response time (<10 seconds) and good reproducibility at a working pH range of 4.0-6.5. The electrode was used for 4 months without any significant change in its sensitivity. The potentiometric performance of the electrode in partially nonaqueous medium [up to 20 % (v/v) alcohol] was found satisfactory. The performance of the prepared electrode for the analysis of beer samples using direct potentiometric method is very encouraging. Copyright (C) 2014, Food and Drug Administration, Taiwan. Published by Elsevier Taiwan LLC. All rights reserved.